Ahhhh, that looks to be an 'Ultimate Speed Potion', use it wisely! You gain 5000xp.
The man hands you a note which reads ... "Mix 2xA, 3xB, 5xC and 7xD". The man comments that if you should manage to obtain anything you should bring it back to him.
Obtain 15 Blue Powder and 20 Red Powder
*Mix them to get
**Green Powder - 8
**Rainbow Powder - 5
*Mix all together:
** 2 x Blue Powder
** 3 x Green Powder
** 5 x Rainbow Powder
** 7 x Red Powder
* into Unidentified Potion
*Start quest Dwarven Mines
*Receive Ultimate Speed Potion (Bound)
*Turn in quest